Simulation of visible light induced effects in a tunnel junction array forphotonic device applications

We have studied visible light or near-infrared irradiation effects in volta ge-biased tunnel junction arrays, where each node is connected nor only to neighboring nodes but to a conducting substrate through a tunnel barrier. M ajor assumptions used in the simulation are: (i) that the photoexcitation o f electrons occurs only in the substrate and (ii) the tunnel barrier is eff ectively lowered for the excited electrons, resulting in a reduced tunnel r esistance. As a result, it was found that a U-shaped potential profile is f ormed by local irradiation and the potential of the irradiated area is clam ped at the lowest value. Since the currents at both terminals reflect the l eft and the right potential slopes in the dark areas, respectively, the irr adiated position is determined by measuring the currents. These results sug gest that tunnel junction arrays can be applied to photonic devices such as position sensing detectors or image processing devices.